I don't have an enormous screen, but I usually only size the windows big enough to fit all of the content. For example if I'm reading a text file, I size the window down as small as it will go without having to scroll left or right to view all of the document.

I upgraded my system to two 24" monitors and i maximize my browser and if I am watching a movie or music video I maximize WMP. I also use Motorola CPS Software (for programming Motorola two-way radios) which I also maximize for ease of use. Other than that I keep everything minimized unless I need it.

I don't prefer to maximize application windows as it wreck my versatile flow between tasks. However, I do size "productivity" or certain application that lack the necessary workspace environment. Photoshop and Microsoft Expression Web seems to have very small workspace inside it's application. But still they are not max. I sometimes prefer my game in full-window mode, but sometimes in windowed mode.

I got myself a 24" sammy 1920x1080 and I have everything I can maximised, because I can't stand scrolling sideways. The exceptions are Winamp, TomTom Home, Avast, Unzbin, AVS Video Converter, Calculator and Notepad.

When I ran dual or triple monitor 4:3 ratio, almost everything was used maximized. However, now that I am running dual 24" widescreen monitors it's a mixed bag of what gets maximized. Especially with the Windows 7 Win-Left, Win-Right happy goodness that has changed my productivity forever.

I maximize browsers, media players, games, virtual machines, ps and stuff like that. Only stuff that doesnt get maximized is chat screens. (Steam, I use gtalk in browser or via the new chat extension for chrome.)

Since I use a 46 inch tv and a laptop monitor it's pretty easy to manage and tons of small screens don't work well on a tv. (I'm sitting with in 3 feet of the tv, probably horrid for my eyes but I can read most things very well and for single player games it works better. I also use the TV for browsing. Multiplayer games like LoL or anything too reliant on skill I pop on the laptop monitor just because it feels more responsive.) I freaking hate alt tabbing and I hate using windows explorer. (Running w8 and even with ribbon the explorer is a pain to manage anything with.)